Experimental infection of Corbicula fluminea (Bivalvia: Corbiculidae) with Echinostoma revolutum cercariae.
None of the 25 C. fluminea from the Schuylkill river, USA, examined in 1986 contained E. revolutum cercariae. When 4 wild C. fluminea (14 mm shell diameter) were exposed to 1000 cercariae (shed by Helisoma trivolvis) all were infected on necropsy 4 days later with 5 to 36 cysts/clam. A further experiment involving 11 clams, showed that: the cyst recovery rate was 24.7% of infection dose; 90% of these were viable; 260 of the 272 cysts recovered were found in the gills, 7 in the kidneys and 5 in the visceral mass-foot region. Exposure to alkaline trypsine-bile salt at 41°C induced excystment of some of the larvae which started after 2 h. In a comparative experiment 5 cysts were recovered from 4 C. fluminea and 189 from 4 Biomphalaria glabrata.<new para>ADDITIONAL ABSTRACT:<new para>[In a subsequent paper (pp. 1047-1048) Fried, S. Scheuermann and J. Moore report that of several laboratory-raised pulmonate snails tested only the Pennsylvania strain of Helisoma trivolvis was susceptible to infection with miracidia of the Pennsylvania strain of Echinostoma revolutum.]